Metering gear pumps operate by moving viscous fluid between meshing gears. Typically, the gears are mounted within stacked plates which are appropriately ported to receive viscous fluid between the gears and discharge the fluid usually in one or more streams depending on the number of gears and outlet ports. In a simple metering gear pump, there will be a single inlet port and a single outlet port. The inlet port communicates with an inlet space adjacent to the meshing gears and the outlet port communicates with an outlet space between the meshing gears. In the case of external gears, the two meshing gears will create suction drawing the fluid into the inlet space. As the gears rotate, they separate on the inlet side of the pump, creating a void and suction which is filled by the fluid. The fluid is carried by the gears to the discharge or outlet side of the pump, where the meshing of the gears displaces the fluid from the outlet space between the gears and through the outlet port. The mechanical clearances within a gear pump are typically small and these tight clearances, as well as the viscosity of the fluid and gear speed, will force the fluid continually from the inlet side of the pump to the outlet side of the pump.
There may be instances in various applications, including manufacturing operations, in which the gears of a metering gear pump will rotate but fluid will not adequately flow through the pump. In order to ensure that operating personnel are quickly notified in this situation, various measures are taken. For example, one or more flow meters or pressure transducers are used in the fluid system downstream from the pump to provide a monitoring function. If a flow meter or pressure transducer indicates that flow in the system is inadequate, the production line may be shut down for troubleshooting and maintenance purposes.
It would be desirable to provide a simpler and potentially less expensive manner of monitoring proper fluid metering from a gear pump.